.TH std::invalid_argument 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::invalid_argument \- std::invalid_argument

.SH Synopsis
   Defined in header <stdexcept>
   class invalid_argument;

   Defines a type of object to be thrown as exception. It reports errors that arise
   because an argument value has not been accepted.

   This exception is thrown by std::bitset::bitset, and the std::stoi and std::stof
   families of functions.

   std-invalid argument-inheritance.svg

                                   Inheritance diagram

.SH Member functions

   constructor   constructs a new invalid_argument object with the given message
                 \fI(public member function)\fP
   operator=     replaces the invalid_argument object
                 \fI(public member function)\fP

std::invalid_argument::invalid_argument

   invalid_argument( const std::string& what_arg );   \fB(1)\fP
   invalid_argument( const char* what_arg );          \fB(2)\fP
   invalid_argument( const invalid_argument& other ); \fB(3)\fP (noexcept since C++11)

   1) Constructs the exception object with what_arg as explanatory string. After
   construction, std::strcmp(what(), what_arg.c_str()) == 0.
   2) Constructs the exception object with what_arg as explanatory string. After
   construction, std::strcmp(what(), what_arg) == 0.
   3) Copy constructor. If *this and other both have dynamic type std::invalid_argument
   then std::strcmp(what(), other.what()) == 0. No exception can be thrown from the
   copy constructor.

.SH Parameters

   what_arg - explanatory string
   other    - another exception object to copy

.SH Exceptions

   1,2) May throw std::bad_alloc.

.SH Notes

   Because copying std::invalid_argument is not permitted to throw exceptions, this
   message is typically stored internally as a separately-allocated reference-counted
   string. This is also why there is no constructor taking std::string&&: it would have
   to copy the content anyway.

   Before the resolution of LWG issue 254, the non-copy constructor can only accept
   std::string. It makes dynamic allocation mandatory in order to construct a
   std::string object.

   After the resolution of LWG issue 471, a derived standard exception class must have
   a publicly accessible copy constructor. It can be implicitly defined as long as the
   explanatory strings obtained by what() are the same for the original object and the
   copied object.

std::invalid_argument::operator=

   invalid_argument& operator=( const invalid_argument& other    (noexcept since C++11)
   );

   Assigns the contents with those of other. If *this and other both have dynamic type
   std::invalid_argument then std::strcmp(what(), other.what()) == 0 after assignment.
   No exception can be thrown from the copy assignment operator.

.SH Parameters

   other - another exception object to assign with

.SH Return value

   *this

.SH Notes

   After the resolution of LWG issue 471, a derived standard exception class must have
   a publicly accessible copy assignment operator. It can be implicitly defined as long
   as the explanatory strings obtained by what() are the same for the original object
   and the copied object.

Inherited from std::logic_error

Inherited from std::exception

.SH Member functions

   destructor   destroys the exception object
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP
   what         returns an explanatory string
   \fB[virtual]\fP    \fI(virtual public member function of std::exception)\fP

.SH Notes

   The purpose of this exception type is similar to the error condition
   std::errc::invalid_argument (thrown in std::system_error from member functions of
   std::thread) and the related errno constant EINVAL.

.SH Example


// Run this code

 #include <bitset>
 #include <iostream>
 #include <stdexcept>
 #include <string>

 int main()
 {
     try
     {
         std::bitset<4>{"012"}; // Throws: only '0' or '1' expected
     }
     catch (std::invalid_argument const& ex)
     {
         std::cout << "#1: " << ex.what() << '\\n';
     }

     try
     {
         [[maybe_unused]] int f = std::stoi("ABBA"); // Throws: no conversion
     }
     catch (std::invalid_argument const& ex)
     {
         std::cout << "#2: " << ex.what() << '\\n';
     }

     try
     {
         [[maybe_unused]] float f = std::stof("(3.14)"); // Throws: no conversion
     }
     catch (std::invalid_argument const& ex)
     {
         std::cout << "#3: " << ex.what() << '\\n';
     }
 }

.SH Possible output:

 #1: bitset string ctor has invalid argument
 #2: stoi: no conversion
 #3: stof: no conversion

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

     DR    Applied to       Behavior as published               Correct behavior
   LWG 254 C++98      the constructor accepting const    added
                      char* was missing
                      the explanatory strings of         they are the same as that of
   LWG 471 C++98      std::invalid_argument's            the
                      copies were implementation-defined original std::invalid_argument
                                                         object
